Category Archives: Planets & Moons

Today, Oct. 23rd, most of the United States and Canada will be able to view the partial solar eclipse that will start at about 6pm EST. An eclipse, of course, is when an astronomical body is obscured, either by passing into the shadow of another body or having another body pass between it and the viewer . To mark the occasion I thought it would be interesting if we looked at some other moons in our solar system. So here are ten quick facts about all those moons that orbit the planets.

Besides the Sun and Moon, Venus is the brightest celestial body. It’s so bright that you can even see it during the daytime. Tomorrow morning, and the rest of the week, you can see Venus in the morning sky just before sunrise. That is, if it is a clear sky when you go out. Depending on where you are, Venus is about two fists above the horizon.

NASA is inviting people around the world to submit their names to be etched on a microchip aboard a spacecraft headed to the asteroid Bennu in 2016. The “Messages to Bennu!” microchip will travel to the asteroid aboard NASA’s Origins-Spectral Interpretation Resource Identification Security Regolith Explorer (OSIRIS-REx) spacecraft. The robotic mission will spend more than two years at the 1,760-foot (500-meter)-wide asteroid. The spacecraft will collect a sample of Bennu’s surface and return it to Earth in a sample return capsule.

NASA is proposing this project as a great opportunity for people to get engaged with the mission. Those wishing to participate in “Messages to Bennu!” should submit their name online no later than 30 September, 2014 at: http://planetary.org/bennu

After a person submits their name, they will be able to download and print a certificate documenting their participation in the OSIRIS-REx mission. So, be part of humankind’s exploration of the solar system –How cool is that?

Participants who “follow” or “like” the mission on Facebook will receive updates on the location of their name in space from launch time until the asteroid samples return to Earth in 2023. Facebook fans also will be kept apprised of mission progress and late-breaking news through regular status updates.

The OSIRIS-REx mission goal is to address basic questions about the composition of the very early solar system, the source of organic materials and water that made life possible on Earth, and to better predict the orbits of asteroids that represent collision threats to the Earth. It will collect a minimum of 2 ounces (60 grams) of surface material. Once the sample return capsule deploys, the spacecraft will be placed into a long-term solar orbit around the sun, along with the microchip and every name on it.

There has been lots of talk in Baton Rouge about ice, snow, and cold. Let’s change focus and talk about something hot: volcanoes! The planetarium is about to debut its latest show “Super Volcanoes” which gives audiences a front row seat to some of Earth’s largest volcanic eruptions. The show features extensive live action footage of geothermal features in Yellowstone National Park, as well as a complex simulation of an eruption of the Solar System’s largest active volcano, Loki.

Loki can be found on Jupiter’s moon Io. Named for the Norse God of Mischief (or comic book villain if you prefer), this volcano is considered to be the hottest and most powerful in the Solar System. Loki is officially called Loki Patera which means “Loki Basin”. Loki is not a tall volcano, it has no cone. It is the opposite, a large depression in Io’s surface that is filled with lava. Loki alone puts out more heat than all of Earth’s volcanoes combined!

Volcanism was discovered on Io by Voyager back in the 1970s. Up until this point people thought Earth was the only place with such active geology. Initially it was surprising to discover this much activity on such a tiny world. Scientists thought that since larger bodies (such as the other rocky planets, and larger moons) appeared to have thoroughly cooled and stopped exhibiting signs of active volcanism, tiny bodies such as Io wouldn’t exhibit it either. Voyager snapped photos of Io’s surface, showing large volcanic scars as well as plumes of ash reaching into the skies. Io had even more volcanic activity than Earth!

So why is this? As we rub our hands together to stay warm in this winter weather we’re having here in Baton Rouge, consider the moon Io. Io orbits closest to Jupiter out of the four largest moons. The combination of tidal forces from Jupiter, tidal forces from the other large moons, as well as the shape of Io’s orbit all play a role. The constant tugging on Io is thought to cause friction and internal heat inside the moon. Kind of like when you rub your hands together but a lot more so!

Io has mountains and plains, as well as different types of volcanoes. Loki is thought to be a large lake of lava. Images taken from spacecraft show a large dark depression (almost 130 miles across!) with steep edges. Thermal studies have shown that the surface is extremely hot, likely due to a large pool of lava covered by a thin crust. The crusts of these lava lakes can become disrupted, triggering a wave across the lake. The denser crust sinks below the molten rock beneath causing the lake to resurface itself. Scientists are still unsure about how Loki-type volcanoes form on Io. They could form from a collapsed volcano (this occurs on Earth and they are known as Caldarae), or they could be created from an impact of a large meteor into the surface.

Images of spacecraft have also shown plumes of volcanic material being ejected from Loki that have reached nearly 150 Km above the surface (that’s higher than the International Space Station orbits above Earth!). In “Super Volcanoes” audiences will travel to Loki and witness what this eruption might look like from the surface!

If you haven’t already, check out the trailer for “Super Volcanoes”, opening February 1 at the Irene W. Pennington Planetarium.

Great job everyone on braving our record cold temperatures this week! In some places it got as cold as -16 degrees Fahrenheit! As we work to stay warm, and in some places dig ourselves out of our driveways, lets be thankful that none of us have to endure a winter on Pluto. Current Plutonian temperatures (it’s not even Winter there right now, Summer is just ending) average around -350 degrees Fahrenheit!

Pluto is an extremely difficult object to study, it is tiny and its far away. It is roughly 7.5 billion miles from Earth, and takes 248.1 Earth years to orbit the Sun. Pluto was officially discovered in 1930 by Clyde Tombaugh. Interestingly enough Tombaugh was only 23 years old at the time, an intern of sorts. He was tasked with comparing images of the night sky taken at two week intervals using a device called a blink comparator. It would flip the images quickly back and forth, stars (which don’t change position relative to each other in that short of a time) would appear stationary. However a moving object like an asteroid or planet would appear to move past the stars as the images were flipped. Tombaugh discovered Pluto using this method. Since Pluto’s year is 248 Earth years, and it was discovered in 1930, astronomers have yet to observe Pluto through its entire orbital cycle (which won’t happen until the year 2178).

Tombaugh compared these two plates with the blink comparator and saw Pluto moving relative to the background stars. Source: Lowell Observatory Archives.

We still know very little about Pluto today, our best images are fuzzy, but they can tell us how Pluto changes appearance over time. We know what Pluto’s atmosphere is made out of, which by default can tell us what types of chemicals can most likely be found on the surface. Every chemical has its own unique spectrum (pattern of visible light emitted by the electrons in the atoms as they gain then release energy). By studying the spectra of Pluto, astronomers can pin point the chemicals found there.

Most recent studies of Pluto have monitored the thickness of its atmosphere. How do they do this, you ask? They monitor the light from a star that Pluto passes in front of. This is called a stellar occultation. Studying a stellar occultation of a tiny object that is 7 billion miles away is a very complex and delicate process. Basically astronomers observe changes in the star’s light as it is filtered through Pluto’s atmosphere, these changes can tell us about the atmosphere’s composition and thickness.

What is Plutonian winter like? We don’t entirely know. Recent theories suggest that as Pluto continues to get farther from the Sun in its orbit (as it is doing) and enters into winter time, the surface temperature will drop. This would then cause the atmosphere to freeze out and fall to the ground as a fine snow of nitrogen, carbon monoxide, methane, and other chemicals.

In “The Gravity Factor” it’s the next century, people live on Pluto in a large base station. For leisure, they snowmobile and ski around the snow covered surface. Source: LASM.

In fact, LASM is partnering with Houston Museum of Natural Science to produce a planetarium show called “The Gravity Factor”. It takes place in the next century, and explores the possibility of colonizing the planets and moons, and the type of work and life people would have in the different places. LASM is contributing to the show by producing a segment about astronauts living on Pluto during winter time after the annual snow fall. In the show astronauts living at the Pluto base occupy their free time with snowmobiling and rocket-powered skiing over the snow drifts on the surface. A fun prospect!

Most recent research has suggested an alternative to this theory. Astronomers have been observing Pluto’s atmosphere expecting to see evidence of it thinning as the “snow storm” begins, however they have observed the opposite. Pluto’s atmosphere is staying the same, in fact it appears to be getting thicker. Some scientists believe that this indicates that the snow storm isn’t going to happen (as it should have started by now). They conclude that this is an indication of thermal inertia, the ability for Pluto to retain energy absorbed from the Sun during the Summer. Pluto has higher thermal inertia than previously thought, so its atmosphere is not cooling as quickly as scientists would have expected, despite the planet approaching its Winter season.

Artist’s conception of the New Horizons Spacecraft.

So what does all of this mean? Our knowledge of Pluto is constantly changing as we learn more about this distant world. The New Horizons spacecraft is hurtling towards Pluto at a whopping 31,000 miles per hour, making it one of the fastest spacecraft ever. It will reach Pluto in 2015 and get an up close view of the dwarf planet. Astronomers eagerly anticipating data and imagery from New Horizons will help them gain a better understanding of Pluto. The general public is excited too, for the first time we’ll be able to see what Pluto looks like up close!

Burrr… Feeling the chill of this week’s arctic blast? Much of the country is expecting historic, record breaking low temperatures.

These temperatures, unusual for us here on Earth, are normal for daytime on the planet Mars: minus 13-degrees Fahrenheit (-25 in Celsius). If you think that’s chilly, the Martian nighttime temperature drops precipitously to a minus 125-degrees F.

Image captured by Viking 2 of frost on the Martian surface.

Baton Rouge is expecting a balmy 15 degree Fahrenheit for a low, so enjoy while it lasts.

MAVEN is scheduled to launch in approximately 1 hour. If you are in Florida or South Georgia today you may be able to catch a glimpse of the liftoff. There are some thick clouds over Cape Canaveral Air Force base but the forecast is 60% favorable for launch during a two hour window. .

NASA just released a panoramic image of Saturn and some of its closest moons, but it also includes the tiny, blue dot we call home – planet Earth, some 900 million miles away. Taken by the Cassini probe now orbiting Saturn, the image also captures our companion worlds Venus and Mars. The panorama was pieced together from natural-color photographs taken in July.

Each pixel in the photograph represents about 45 miles. Seven out of Saturn’s 53 known moons are visible in their planet’s seven rings. There’s Prometheus, Pandora, Janus and Epimetheus near Saturn’s slim F ring. There’s Enceladus in the bright blue E ring. There’s Tethys, a yellow bulb, and Mimas, just a crescent, wedged between rings.

Venus is located to Saturn’s upper left, which is seen as a bright, white spot. Mars, a pale red dot, is above and to the left of Venus. There are 809 stars captured by Cassini’s lens in this image. And we Earthlings are on the blue dot at Saturn’s lower right.

This cosmic portrait had been planned for months and on July 19, NASA announced that all the conditions were right for such a picture, including that on this date, Saturn completely eclipsed the sun, allowing Cassini’s sensors to image this portrait. The cosmic photo is a composite of 141 images taken over four hours, selected out of 343 images total. The photograph was then digitally enhanced to pull from the blackness Venus, Mars, Earth, Saturn’s moons, and all the stars in the frame. Most of the objects in the photograph, including Earth, were brightened by 8 times relative to Saturn; some of the stars were brightened by as much as 16 times.

This was also the first time that humans were told in advance that Earth was being put before a camera. So, in what was called NASA’s “Wave at Saturn” campaign, the Cassini’s Imaging team asked us all to turn out for the July 19 picture day to wave and smile for the camera in the cosmos.

“On July 19, 2013, in an event celebrated the world over, NASA’s Cassini spacecraft slipped into Saturn’s shadow and turned to image the planet, seven of its moons, its inner rings — and, in the background, our home planet, Earth.”(NASA)